It's been speculated the sheepfoot shaped blade originated with mariners who found the rounded tip especially beneficial when the knife was accidentally dropped (think working on a ship in pitching seas) as it couldn't stab the foot when hitting the deck. More info...

Limited to 600 pieces of each handle
material, our ongoing Kopa Series launched in 2005 continues to grow.
The Kopa Series introduced Spyderco's first collection of refined
gentlemen's folders. Launched in 2005, the completed Series will be
made up of exceptionally unique handle variations of the same model
knife. Spyderco has been unveiling a new Kopa approximately every 3-4
months and will continue till the collection is complete. Although each
release represents a separate model, Kopas all have a common thread;
their stainless handles are individually fitted with exotic inlays.

All
Kopas have stainless handles engineered for the human hand. Finger
choils position the hand in contact with expansion points on the
handle's underside generating precision over the cutting edge. Kopas'
leaf-shaped blades are VG-10 and flat-ground with a thin, shaving sharp
performance cutting edge. Their back-locks are positioned mid-way on
the spine with a David Boye cutout for added security. Kopas carry
right-handed, tip-down with a silhouette steel pocket clip. PlainEdge
only.